Abstract
A Monte Carlo simulation is used to study the effects of Kappa H+distributions in the polar wind. We consider the gravity, the polarization electric field, the divergence of geomagnetic field lines and Coulomb collisions of H+ in a background of O+ ions. The aim is to study the consequences of a velocity distribution function with an enhanced high energy tail instead of a Maxwellian distribution as assumed in earlier Monte Carlo simulations. The transformation of the velocity distribution function of H+ ions as a function of the altitude is presented. Effects resulting from the acceleration of the particles by the polarization electric field and from Coulomb collisions depend on the energy of the particles. Coulomb collisions mainly affect low energy particles while high energy particles are more efficiently accelerated by the upward directed ambipolar electric field. The combination of both effects results in double-hump velocity distribution functions developing in the transition region. We study consequences of suprathermal tails distributions on the shape of the double-hump and on the moments of the velocity distribution function.
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References
Banks, P.M. and Holzer, T.E.: 1968, The polar wind, J. Geophys. Res. 73, 6846.
Barakat, A.R., Barghouthi, I.A. and Schunk, R.W.: 1995, Double-hump H+ velocity distributions in the polar wind, Geophys. Res. Lett. 22, 1857.
Barakat, A.R. and Lemaire, J.: 1990, Monte Carlo study of the escape of a minor species, Phys. Rev. A 42 (6), 3291.
Barakat, A.R. and Schunk, R.W.: 1983, O+ ions in the polar wind, J. Geophys. Res. 88, 7887.
Barghouthi, I.A., Barakat, A.R., Schunk, R.W. and Lemaire, J.: 1990, H+ outflow in the polar wind: A Monte Carlo simulation, Eos Trans. AGU 71, 1493.
Barghouthi, I.A., Barakat, A.R. and Schunk, R.W.: 1993, Monte Carlo study of the transition region in the polar wind: an improved collision model, J. Geophys. Res. 98, 17583.
Christon, S.P., Mitchely, D.G., Williams, D.J., Frank, L.A., Huang, C.Y. and Eastman, T.E.: 1988, Energy Spectra of Plasma Sheet Ions and Electrons from ~ 50 eV/e to ~ 1 MeV During Plasma Temperature Transitions, J. Geophys. Res. 93, 2562-2572.
Demars, H.G. and Schunk, R.W.: 1987, Comparison of solutions to bi-Maxwellian and Maxwellian transport equations for subsonic flows, J. Geophys. Res. 92, 5969.
Ganguli, S.B.: 1996, The polar wind, Rev. Geophys. 34 (3), 311.
Lemaire, J. and Scherer, M.: 1972, Kinetic models of the solar and polar winds, Rev. Geophys. 11, 427.
Lie-Svendsen, O. and Rees, M.H.: 1996, An improved kinetic model for the polar outflow of a minor ion, J. Geophys. Res. 101, 2415.
Maksimovic, M., Pierrard, V. and Riley, P.: 1997, Ulysses electron distributions fitted with Kappa functions, Geophys. Res. Lett. 24 (9), 1151.
Moore, T.E., Chappell, C.R., Chandler, M.O., Craven, P.D., Giles, B.L., Pollock, C.J., Burch, J.L., Young, D.T., Waite Jr., J.H., Nordholt, J.E., Thomsen, M.F., McComas, D.J., Berthelier, J.J., Williamson, W.S., Robson, R. and Mozer, F.S.: 1997, High-altitude observations of the polar wind, Science 277, 349.
Pierrard, V.: 1997, Fonctions de distribution des vitesses des particules s'échappant de l'ionosphère, PhD thesis, Université Catholique de Louvain, 171 pp.
Pierrard, V. and Lemaire, J.: 1996, Lorentzian ion exosphere model, J. Geophys. Res. 101, 7923.
Pierrard, V. and Lemaire, J.: 1998, A collisional kinetic model of the polar wind, J. Geophys. Res. 103, 11701.
Scudder, J.D.: 1992, On the causes of temperature change in inhomogeneous low-density astrophysical plasmas, Astrophys. J. 398, 299.
Wilson, G.R.: 1992, Semi-kinetic modeling of the outflow of ionospheric plasma through transition region, J. Geophys. Res. 97 (10), 551.
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Barghouthi, I., Pierrard, V., Barakat, A. et al. A Monte Carlo Simulation of the H+ Polar Wind: Effect of Velocity Distributions with Kappa Suprathermal Tails. Astrophysics and Space Science 277, 427–436 (2001). https://doi.org/10.1023/A:1012536114212
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DOI: https://doi.org/10.1023/A:1012536114212